Cigarette Lighter with Refractive Fuel Window

ABSTRACT

The exemplary embodiment is a reservoir for use with a cigarette lighter has a chamber for containing gas and liquid fuel and a lens made of a transparent material and having an internal surface adjacent the chamber. The internal surface allows optical transmission of visible light into and from the liquid fuel when in contact therewith, but denies the transmission of light into the gas when in contact therewith. The internal surface is contoured such that the transmissions are facilitated by optical refraction, and the denial is facilitated by optical reflection. The transmissions facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber. The chamber has within a non-transparent object viewable through the lens during the transmissions and non-viewable through the lens during the denial. The object is a planar panel disposed substantially parallel to and displaced from the internal surface. Indicia proximate the lens may be provided for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber. The reservoir may be removable from the lighter for replacement and the lens may be viewable through a window in the lighter&#39;s housing.

RELATED APPLICATION

This application is a Continuation-in-Part and claims the benefit of U.S. Utility application Ser. No. 11/854,015, filed Sep. 12, 2007, the entire teachings of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is related to cigarette lighting apparatuses and the containment of flammable liquid fuel therein.

BACKGROUND

Liquid fuel burning cigarette lighters generally include reservoirs within the lighter housings to contain the fuel. Some such reservoirs are made of a transparent material to allow the user to view through the reservoir to observe the amount of fuel within. But because liquid fuels, such as liquefied butane, are generally colorless as is air, a reservoir filled with fuel can appear virtually identical at first glance to a reservoir that is completely empty of fuel and filled with air. When the reservoir is partially filled, the user must therefore look carefully for the interface line between the liquid fuel and the air to determine the relative amounts of each. The thin interface line can be difficult to see under even the best lighting conditions. For far-sighted users, it can be impossible to see this thin line and to therefore gauge the amount of fuel in the reservoir.

Such difficulties are problematic not only when trying to ascertain the amount of fuel remaining in the lighter to avoid running out of fuel, but are also problematic when attempting to refuel the lighter. Because butane is gaseous at standard temperatures and pressures, it must be stored in a pressurized state in order to remain liquid. Lighters are typically equipped with a one-way inlet valve to allow the intake of pressurized liquefied butane into the reservoir from an external pressurized supply tank. When transferring the liquefied butane from a pressurized supply tank to the lighter reservoir through the valve, one must observe the amount of fuel within the tank to avoid overfill, lest the fuel will overflow at the valve, and become an invisible and dangerous gas. Users often refuel the reservoirs far past the point where they are filled, just to be sure the reservoirs have been fully refueled, thereby wasting significant amounts of expensive fuel and creating a hazardous situation until the spilled fuel has dissipated.

There exists a need for improvement in the viewing of fuel within the reservoirs of liquid fuel burning lighters, and such is an object of the present invention. There exists the need for improvement in the convenience of refueling such lighters, and such is another object of the present invention. There exists the need for improvement in the safety of refueling such lighters, and such is another object of the present invention. There exists the need for improvement in the economy of refueling such lighters, and such is another object of the present invention. There exists the need for improvement in the convenience of gauging the need for refueling such lighters, and such is another object of the present invention. And there exists the need for improvement in the efficacy of gauging the need for refueling such lighters, and such is another object of the present invention.

U.S. Pat. Nos. 6,939,128, 6,733,277, 6,478,575, 6,443,727, 6,431,853, and 5,531,591 teach mechanisms and means for releasing, lighting, and extinguishing fuel in state-of the art liquid fuel burning lighters. Such mechanisms and means may be adaptable to a lighter of the present invention and are therefore anticipated for use within the present invention, and the specifications of these patents are incorporated herein by reference.

SUMMARY OF THE INVENTION

The invention includes, in combination, a cigarette lighter and a fuel reservoir for use therein where the fuel reservoir enhances the ability to gauge the amount of liquid fuel, air, or the relative amounts of both within. The invention also includes such a fuel reservoir alone. The invention further includes a method for gauging the amount of liquid fuel, air, or the relative amounts of both within such a reservoir.

The reservoir may be removable from the lighter, such as when the reservoir is empty, for replacement with a filled reservoir to avoid the need and danger of refilling the reservoir in the lighter from a pressurized fuel supply. This replaceability is not critical to the practice of the invention, but is taught in more detail, absent the gauging enhancement features, in co-pending and related application Ser. No. 11/854,015, which teachings are incorporated herein by reference in their entireties.

The reservoir has a chamber for containing a flammable liquid fuel, which may be contained under pressure, and for supplying the fuel to the ignition means of the lighter. The reservoir may have a first valve having a closed state for denying escape of the fuel from the reservoir and an open state for allowing such escape to the ignition means for lighting. The reservoir may have a second valve for allowing fuel to enter the reservoir under pressure during refilling. The lighter may have an ignition actuator for causing ignition of the escaped fuel when the ignition actuator is actuated, a nozzle for causing the ignited fuel to form a lighting flame, and a valve actuator cooperating with the ignition actuator to open the first valve as the ignition actuator is actuated.

The reservoir has a lens made of a transparent material and having an internal surface adjacent the chamber. The internal surface allows optical transmission of visible light into and from the liquid fuel when in contact therewith, but denies the transmission of light into the gas when in contact therewith. The internal surface may be contoured such that the transmissions are facilitated by optical refraction, and the denial is facilitated by optical reflection. The transmissions may facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber. The chamber may have within a non-transparent object viewable through the lens during the transmissions and non-viewable during the denial. The object may be a planar panel disposed substantially parallel to and displaced from the internal surface. Indicia proximate the lens may be provided for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber. The lens may be viewable through a window in the lighter's housing.

While the term “cigarette” is used throughout this specification and its appended claims, it is anticipated that such a lighter could be used for any similar purpose, such as lighting cigars and smoking pipes. Therefore, the term “cigarettes” is meant to include any such smoking device whenever the term is used in this specification of the appended claims.

Further features and aspects of the invention are disclosed with more specificity in the Detailed Description and Drawings of an exemplary embodiment provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a perspective view of a lighter according to an exemplary embodiment of the invention,

FIG. 2 is a side view of the lighter of FIG. 1,

FIG. 3 is a cross-sectional side view of the lighter of FIG. 1 in use,

FIG. 4A is a cross-sectional top view through the chamber and liquid fuel of the lighter of FIG. 1, taken at view line 4A of FIG. 3, and of the lighter of FIG. 1 during insertion of its fuel cartridge,

FIG. 4B is a cross-sectional top view through the chamber and gas of the lighter of FIG. 1, taken at view line 4B of FIG. 3, and

FIG. 4C is an enlargement of FIG. 4B showing various rays of light being reflected.

DETAILED DESCRIPTION

Reference is now made to FIGS. 1 through 4C, where there is shown an exemplary cigarette lighter 100 in accordance with just one of the infinite number of possible lighters of the present invention, and a fuel cartridge 102 in accordance with just one of the infinite number of possible reservoirs of the present invention

Lighter 100 includes a housing 126 having an opaque shell 128 which surrounds fuel cartridge 102. The cartridge is a reservoir having a chamber 122 for containing pressurized and flammable liquid fuel 106. As a by-product of the consumption of fuel during lighting, the chamber will generally also contain some gas 108, in the form of either air, the gaseous state of the fuel, or a combination thereof.

The lighter 100 includes a piezo-electric igniter and igniting process in accordance with the teachings of co-pending and related application Ser. No. 11/854,015, or equivalent components may otherwise be included in accordance with any of those described in further detail in the previously mentioned U.S. Pat. Nos. 6,939,128, 6,733,277, 6,478,575, 6,443,727, 6,431,853, and 5,531,591, or the invention may be used within virtually any type of lighter having a reservoir for containing liquid fuel.

As detailed in co-pending and related application Ser. No. 11/854,015, cartridge 102 is removable from lighter 100 to provide a convenient and economical method for replacing depleted fuel, and an advantageous manner for manufacturers to sell pre-filled fuel cartridges at a cost far lower than the cost of replacing an entire lighter. Such an arrangement also provides a safety advantage over refilling the lighter from an external fuel source. However, such removability and replaceability of the cartridge are not requirements of the present invention.

For those users inclined to refuel from an external source, cartridge 102 may include refueling port 148, as detailed in co-pending and related application Ser. No. 11/854,015, for optionally allowing refueling of the cartridge from an external fuel source, which refueling can be done safety apart from the lighter and it's ignition means by simply removing the cartridge prior to refueling. However, such a port is not a requirement of the present invention.

Another aspect of lighter 100 and cartridge 102, as detailed in co-pending and related application Ser. No. 11/854,015, is the improvement which the combination provides for gauging the need for refueling. The lighter's opaque housing shell 128 includes a viewing window 130 though which the user may see the cartridge 102 when it is within the housing 126. The cartridge is transparent in at least the portion forming a lens 124 adjacent window 130 so that the user may view through the window 130 and lens 124 to see the amount of fuel 106 remaining within the cartridges fuel chamber 122. Indicia may be molded into, embossed onto, or printed onto the lens 124, or onto an adjacent outside surface of shell 128, to allow observation of the relative amount of fuel remaining, in accordance with the teachings of co-pending and related application Ser. No. 11/854,015. However, such a window and such indicia are not requirements of the present invention.

Lens 124 is preferably made of a made of a transparent, colorless and solvent-resistant material having a refractive index closer to that of the liquid fuel than to that of air or gas. For instance, the lens may be made of clear Trogamid T5000 semi-crystalline polyamide having a refractive index of approximately 1.5. The typical fuel may be liquid butane, having a refractive index of approximately 1.5, and the refractive indexes of invisible gases, such as air and gaseous butane, are approximately 1.

Lens 124 has a planar outer surface 132. The outer surface may alternatively be curved either longitudinally, transversely, or both, but should preferably be a smooth and transparent surface capable of transmitting visible light directly into the lens from affront the lighter so that a user may peer into the lens through window 130.

Lens 124 has a prismatic internal surface 142, which is preferable contoured with triangular longitudinal ridges 144 that are disposed adjacent the chamber, to contact either the liquid fuel 106 or the gas 108. The ridges shown may alternatively be replaced by inwardly pointing pyramidal protrusions or some equivalent thereto, which, as will be further explained allow optical transmission of visible light through the internal surface and into or from the liquid fuel, but deny such transmission of light through the internal surface and into the gas.

In order to accomplish such transmission and denial, the contouring of internal surface 142 provides optical refraction into and from the liquid fuel to provide the transmissions, and optical reflection to cause the denial. The optical reflection of internal surface 142 causes an image to the user of vertical white and black striping reflected by the longitudinal ridges 144 of the internal surface.

The transmissions facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber, by allowing the user to see into chamber 122 only in the area where liquid fuel 106 is present, but to see only an internal reflection in the area where gas 108 is present, thus enabling an instant comparison of the relative amounts of liquid fuel and gas within chamber 122.

Within chamber 122 is disposed an object 180, which is preferably a brightly colored panel disposed substantially parallel to and displaced from said internal surface 142. Only when enabled to see into the chamber 122 by the presence of liquid fuel may the user see the brightly colored panel 180. For instance, using a preferably bright red panel causes the colorless liquid fuel to appear bright red, when any gas in the chamber which may lie directly atop the liquid fuel will have the black and white vertical striping appearance of the longitudinal ridges 144. The distinction between the bright red portion of the chamber containing liquid fuel and the portion not containing fuel is instantly obvious, allowing even far-sighted users to immediately appreciate the amount of fuel in their lighter; a fully red image meaning the lighter is completely fueled, a fully striped image meaning the lighter is completely empty, and an image that is partly red and partly striped allowing an instant comparison of the fuel-to-air ratio and a gauging of the need to refuel the lighter or replace the cartridge.

As compared to prior art lighters with transparent fuel reservoirs that cause the gas and fuel within to appear virtually identical at first glance and that require the user to find the very thin line separating the liquid fuel and the gas, the present invention causes the fuel level within the lighter to be instantly visible to the user.

The optical phenomenon of total internal reflection is employed to alter the view into the chamber when the chamber is filled with gas versus liquid fuel. Total internal reflection takes place when a light ray (and hence a ray of vision) is in the more dense medium and approaching the less dense medium, and the angle of incidence for the light ray is greater than the critical angle θ_(crit). When chamber 122 is gas-filled, the medium (gas 108) in the chamber is less dense than the medium of lens 124 and a critical angle may exist. When chamber 122 is liquid-filled, the medium (liquid fuel 106) in the chamber is equally dense as the medium of lens 124 and a critical angle may not exist.

When the gas 108 is within chamber 122 adjacent internal surface 142, rays of light (and hence rays of vision) through lens 124 that then impinge on surface 142 at an angle above θ_(crit) will be denied transmission through the surface, and will be totally reflected back into the first medium, lens 124, at a “mirror” angle respective the angle of impingement on the interface surface. The angles of incidence and refraction are measured from perpendicular to the interface at the point of impingement.

The critical angle for the interface between lens 124, made of a material having a refractive index IR₁ of 1.5, and gas 108, having a refractive index IR₂ of 1, is calculated using Snell's Law;

θ_(crit)=(IR ₂ /IR ₁)=sin⁻¹( 1/1.5)=41.8 degrees,

So a ray impinging surface 142 at an angle of greater than 41.8 degrees will be totally internally reflected, as shown in FIGS. 4B and 4C, at an angle relative the surface at the impingement point that “mirrors” the angle of impingement. For example, a ray impinging surface 142 at a forty-five degree angle of incidence will be reflected at minus forty-five degrees, and a ray impinging the surface at a sixty degree angle of incidence (thirty degrees off the surface) will be reflected at minus sixty degrees.

As can be appreciated, light passing between two media of identical refractive indices, such as light (or vision) passing through lens 124 into a liquid fuel filled chamber 122, is unaffected (and light passing between two media of similar refractive indices is barely affected) simply because the interface is virtually ineffective between materials of similar refractive indices . . . it effectively does not exist in an optical sense.

FIG. 4A shows how rays of light or vision 160A impinge normal to outer surface 132, and are therefore uneffected by the outer surface as they pass into lens 124. The rays then impinge on the interface between the lens and the liquid fuel 106 at internal surface 142, but since the lens and liquid fuel have the same refractive indices, the interface is optically insignificant and the rays pass directly through the interface and enter the chamber as rays 160B, allowing viewing of panel 180. The user is able to view into the liquid fuel as if the lens was invisible and see panel 180. In such a liquid-filled situation, any contouring or angle, or even a lack of contouring, of internal surface 142 would perform equivalently, because the interface is essentially nonexistent when the transition across the interface is between media of similar refractive indices. Such transmission is also referred to as reversible due to the fact that if all conditions were identical, the interface be inherently the same for light propagating in the opposite direction, allowing the transmission of the image from within the chamber to be viewed in the presence of liquid fuel.

As can be seen in FIGS. 4A to 4C, longitudinal ridges 144 preferably have surfaces disposed at forty-five angular degrees from the direction of rays 160A. When the chamber is gas-filled or the internal surface is adjacent to gas, this provides not only an angle of incidence beyond the critical angle and the resulting internal reflection for a lens-to-gas interface for most frontal viewing, but also provides a preferable one-hundred and eighty degree “reverse reflection” for most frontal viewing.

Such reflection and the denial of view into the gas-filled chamber is shown in FIG. 4B, which is identical to the scenario depicted in FIG. 4A, except the chamber is now gas-filled and the interface at internal surface 142 is now from the lens 124 having a high refractive index of 1.5 to air having a much lower index of 1.0. In this case, the interface is effective and the critical angle of incidence comes into play to cause the reflection of rays 160A into rays 160C.

As shown in FIG. 4C, as entering rays of light (or of vision) 160A, 160D and 160F enter the lens at various typical angles of view, they impinge on and are reflected by a first forty-five degree surface to a second “mirroring” forty-five degree surface, and are then reflected back towards the viewer as reflected rays 160C, 160E and 160G, respectively, travelling exactly opposite their original direction, perfectly parallel to their respective entering rays 160A, 160D and 160F. Any angle of incidence on surface 142 beyond the critical angle will provide equivalent reflective results.

And while the longitudinal ridges shown or the pyramidal protrusions mentioned would preferable have surfaces disposed at 45-degrees, any contouring or surface angling that causes internal reflection for most anticipated angles of viewing would be somewhat effective and within the intended scope of the invention, although possibly not resulting in the same perfectly reversed reflection. The opposing forty-five degree surfaces on the internal surface, whether by way of horizontal or vertical ridges or by way of pyramidal protrusions, are found to provide a distinct and true reverse reflection, substantially independent of the angle by which users generally try to view into the chamber, as shown in FIG. 4C.

In Summary, this exemplary embodiment of the invention includes, in combination and separately, a lighter with a reservoir having a chamber for containing gas and liquid fuel and a lens made of a transparent material and having an internal surface adjacent the chamber. The internal surface allows optical transmission of visible light into and from the liquid fuel when in contact therewith, but denies the transmission of light into the gas when in contact therewith. The internal surface is contoured such that the transmissions are facilitated by optical refraction, and the denial is facilitated by optical reflection. The transmissions facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber. The chamber has within a non-transparent object viewable through the lens during the transmissions and non-viewable during the denial. The object is a planar panel disposed substantially parallel to and displaced from the internal surface. Indicia proximate the lens may be provided for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber. The reservoir may be removable from the lighter for replacement and the lens may be viewable through a window in the lighter's housing.

While the invention has been shown and described with reference to a specific exemplary embodiment, it should be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention, and that the invention should therefore only be limited according to the following claims, including all equivalent interpretation to which they are entitled. 

1. A reservoir for use with a cigarette lighter and comprising: a chamber for containing gas and liquid fuel; a lens made of a transparent material disposed in a window through a vertical sidewall of said chamber and having a vertically constant horizontal cross-sectional shape and an internal surface adjacent the chamber, wherein said internal surface is comprised of vertically disposed and parallel triangular longitudinal ridges and thereby allows optical transmission of visible light into the liquid fuel when in contact therewith, but denies said transmission of light into the gas when in contact therewith.
 2. The reservoir of claim 1 wherein said internal surface further allows return optical transmission of visible light from the liquid fuel when in contact therewith.
 3. The reservoir of claim 2 wherein said internal surface is contoured such that said transmissions are facilitated by optical refraction, and said denial is facilitated by optical reflection.
 4. The reservoir of claim 3 wherein said transmissions facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber.
 5. The reservoir of claim 4 wherein said chamber further comprises a non-transparent object viewable through said lens during said transmissions and non-viewable through said lens during said denial.
 6. The reservoir of claim 5 wherein said object is a planar panel disposed substantially parallel to and displaced from said internal surface.
 7. The reservoir of claim 6 further comprising indicia proximate said lens for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber.
 8. A cigarette lighter comprising: a chamber for containing gas and liquid fuel; a lens made of a transparent material disposed in a window through a vertical sidewall of said chamber and having a vertically constant horizontal cross-sectional shape and an internal surface adjacent the chamber, wherein said internal surface is comprised of vertically disposed and parallel triangular longitudinal ridges and thereby allows optical transmission of visible light into the liquid fuel when in contact therewith, but denies said transmission of light into the gas when in contact therewith.
 9. The lighter of claim 8 wherein said internal surface further allows return optical transmission of visible light from the liquid fuel when in contact therewith.
 10. The lighter of claim 9 wherein said internal surface is contoured such that said transmissions are facilitated by optical refraction, and said denial is facilitated by optical reflection.
 11. The lighter of claim 10 wherein said transmissions facilitate comparisons of the relative amounts of the liquid fuel and the gas in the chamber.
 12. The lighter of claim 11 wherein said chamber further comprises a non-transparent object viewable through said lens during said transmissions and non-viewable through said lens during said denial.
 13. The lighter of claim 12 wherein said object is a planar panel disposed substantially parallel to and displaced from said internal surface.
 14. The lighter of claim 13 further comprising indicia proximate said lens for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber.
 15. A method of gauging the amounts of liquid fuel and gas in the reservoir of a cigarette lighter comprising: providing within the reservoir a chamber for containing the gas and the liquid fuel; providing of the reservoir a lens made of a transparent material disposed in a window through a vertical sidewall of said chamber and having a vertically constant horizontal cross-sectional shape and an internal surface comprised of vertically disposed and parallel triangular longitudinal ridges adjacent the chamber; allowing through said internal surface optical transmission of visible light into the liquid fuel when in contact therewith; and denying through said internal surface said transmission of light into the gas when in contact therewith.
 16. The method of claim 15 further comprising the step of allowing through said internal surface return optical transmission of visible light from the liquid fuel when in contact therewith.
 17. The method of claim 16 further comprising the step of contouring said internal surface such that said allowings are facilitated by optical refraction, and said denying is facilitated by optical reflection.
 18. The method of claim 17 further comprising the step of comparing via said transmissions the relative amounts of the liquid fuel and the gas in the chamber.
 19. The method of claim 18 further comprising the step of providing within said chamber a non-transparent object viewable through said lens during said transmissions and non-viewable through said lens during said denial.
 20. The method of claim 19 further comprising the step of providing indicia proximate said lens for facilitating the comparison of the relative amounts of the liquid fuel and the gas in the chamber. 